The present invention is directed to the field of controllable dampers. More particularly, the present invention is directed to a controllable seat suspension damper system and a method for dynamically controlling such a damper system.
Various seat damper systems have been proposed for use in Class 8 trucks, off-highway equipment, boat seats, automotive and aerospace applications. Most of the systems used to date are passive, i.e., have a coil or air spring with fixed operational characteristics. A compromise must be made in such systems between providing the desired control for high amplitude vibration and providing the desired isolation from high frequency disturbances. Such tuned passive systems can result in poor ride conditions which produce discomfort for the operator and, in some cases, can lead to loss of control of the vehicle.
One controllable seat damper known in the art is described and claimed in U.S. Pat. No. 5,358,305 issued to Kaneko et al. Kaneko et al. employs a hydraulic seat damper with a controllable valve which can be switched between a closed and an open position, limiting the adjustment to a single hard and a single soft position.
The present invention provides a greater degree of control of the damping force the system provides. Since the damper of the present invention employs a controllable fluid and, because of the particular control method implemented, the present invention can provide a continuous control of the output force of the damper system over a significant range. A single position sensor can provide the necessary input to permit the desired adjustment. Null bands avoid transmission of high frequency vibrations to the seat occupant. The use of end stop limits can increase the damping force when the damper is about to bottom (or top) out thereby avoiding the harsh feel of an end stop collision.
By employing any of a number of additional sensors such as a brake sensor, a clutch sensor, seat occupant sensor, gearshift position sensor, steering angle sensor, speed sensor, rollover sensor, additional features can be provided or existing features can be enhanced. A seat leveling switch can be provided to maintain the seat at a desired height. In addition, a manual ride-mode switch may be provided to allow the driver to select the level of damping desired for the type of driving s/he is doing or the particular feel s/he prefers.
Various other features, advantages and characteristics of the device and control method of the present invention will become apparent after a reading of the following detailed description and addended claims.